Retinal camera

Abstract

To make it possible to simply and positively estimate on the spot the quality of the retinal photographing result, a retinal camera provided with an automatic exposure controlling device, an estimate reference signal generating means, a quality estimating means estimating the quality of the photographing result and an estimation indicating means indicating the estimation result. The automatic exposure controlling device comprises an integrator integrating the output from a light receiving element, a keyboard putting in exposure conditions, an exposure data signal generating means, a reference voltage generating means, a comparative calculating means and a flash light emission controlling means.

What is claimed is: 
     
       1. A retinal camera comprising: automatic exposure controlling means for emitting a flash emission starting signal to initiate a flash output, a flash emission stopping signal indicative of a predetermined amount of light from said flash being received, and an exposure data signal indicative of exposure conditions;   estimate reference signal generating means, connected to said automatic exposure controlling means, for producing an estimate reference signal indicative of a time that should elapse between said flash emission starting signal and said flash emission stopping signal if a proper subject is exposed by said camera, based on said exposure data signal and said flash emission starting signal from said automatic exposure controlling means;   quality estimating means, connected to said automatic exposure controlling means and said estimate reference signal generating means, for determining whether said flash emission stopping signal from said automatic exposure controlling means is produced within a predetermined time threshold of said estimate reference signal and producing an estimating signal indicative thereof, thereby estimating if a proper subject is exposed by said camera; and   estimation indicating means connected to said quality estimating means, for indicating said estimation result on the basis of the estimating signal emitted from said quality estimating means.   
     
     
       2. A retinal camera according to claim 1 wherein said estimation indicating means includes therein a lamp for indicating that the photographing result is good and a buzzer for indicating that the photographing result is not good. 
     
     
       3. A retinal camera according to claim 2 wherein said lamp indicates said good result by flickering. 
     
     
       4. A retinal camera according to claim 1 further comprising a keyboard for inputting said exposure data signal. 
     
     
       5. A camera as in claim 1 wherein said automatic exposure controlling means includes an integrator for integrating an amount of light received and producing said flash emission stopping signal when said predetermined amount of light is received. 
     
     
       6. A camera as in claim 1 wherein said quality estimating means estimates an erroneous exposure when said flash emission stopping signal is produced less than a predetermined time threshold before said estimate reference signal. 
     
     
       7. A camera as in claim 1 wherein said quality estimating means estimates an erroneous exposure when said flash emission stopping signal is produced more than a predetermined time threshold after said estimate reference signal. 
     
     
       8. A camera as in claim 7 wherein said quality estimating means also estimates an erroneous exposure when said flash emission stopping signal is produced more than a predetermined time threshold before said estimate reference signal. 
     
     
       9. A retinal camera for photographing an object that is to be irradiated by a photographic flash, comprising: light receiving means for receiving a reflection of a flash from said object to be photographed and producing an output indicative thereof;   automatic exposure controlling means, connected to said light receiving means, and including:   (a) integrator means for integrating the output from said light receiving means, and   (b) means for determining rate of rising of an output of said integrator means at a predetermined time point,   said automatic exposure controlling means for emitting a flash emission starting signal to initiate said flash, and for producing a flash emission stopping signal when said output of said integrator means reaches a predetermined level and an exposure data signal;   estimate reference signal generating means, connected to said automatic exposure controlling means, for producing an estimate reference signal indicative of a time beginning at said flash emission starting signal, and after which said flash emission stopping signal should be received, if a proper subject is exposed by said camera, as a reference for estimating the quality of a photographing result, and based on said exposure data signal and said flash emission starting signal from said automatic exposure controlling means, and for producing signals indicative of an upper limit value and a lower limit value indicative of a permissible range around said estimate reference signal;   quality estimating means, connected to said automatic exposure controlling means and said estimate reference signal generating means, for comparing the integrated output from said integrator means with said two signals corresponding to said lower limit value and said upper limit value from said estimate reference signal generating means; and   estimation indicating means, connected to said quality estimating means, for indicating an estimation result based on said estimating signal from said quality estimating means.   
     
     
       10. A retinal camera according to claim 9 further comprising keyboard means for inputting said exposure data signal. 
     
     
       11. A retinal camera according to claim 9 wherein said estimation indicating means includes therein a lamp for indicating that the photographing result is good and a buzzer for indicating that the photographing result is not good. 
     
     
       12. A retinal camera according to claim 11 wherein said lamp indicates said good result by flickering. 
     
     
       13. A camera as in claim 9 wherein said quality estimating means estimates an erroneous exposure when said flash emission stopping signal is produced less than a predetermined time threshold before said estimate reference signal. 
     
     
       14. A camera as in claim 9 wherein said quality estimating means also estimates an erroneous exposure when said flash emission stopping signal is produced more than a predetermined time threshold after said estimate reference signal. 
     
     
       15. A camera as in claim 14 wherein said quality estimating means also estimates an erroneous exposure when said flash emission stopping signal is produced more than a predetermined time threshold before said estimate reference signal.